The primary objective this proposal is to produce an understanding of the developmental sequence, correlates, and long-term significance of preschool children's emergent literacy skills and to use this knowledge to improve (a) early identification of children at risk for reading disabilities, (b) the understanding of the developmental and causal relations between preschool emergent literacy skills and the acquisition of beginning reading skills, and (c) the understanding of potential pathways to provide early intervention for children at risk of reading disabilities. The proposed project involves two longitudinal studies. One represents a longitudinal investigation of an existing large cohort of 2-, 3-, 4-, and 5- year-old children recruited for the applicant's ongoing cross-section study concerning the measurement of phonological processing skills in prereaders. The proposed study will provide longitudinal assessments of these children 1-1/2 years from their initial assessment (n greater than 130 per age-group) and yearly thereafter until children are in the third grade. The second study involves an intensive examination of growth in phonological processing skills during the middle and late preschool period (i.e., from 3 to 4 and from 4 to 5) using growth curve modeling and a two-year longitudinal follow-up period. There are six specific aims for this proposal, three with primarily practical importance and three with primarily theoretical importance. The first aim is to identify the preschool skills and time period that are most valid for identifying children who will develop reading disabilities. We will achieve this aim by using latent means and covariance structure analyses in structural equation modeling (SEM) and discriminant/logistic regression analyses (D/LR) on the longitudinal data from Study 1 to identify preschool predictors of reading disability. The second aims is to track the high degree of growth in phonological processing abilities that occurs in the later preschool period, determine the factors that influence the rate of growth, and examine the rate and timing of this growth as a predictor of reading disability. We will achieve this aim by using growth curve modeling on data obtained in Study 2 and by applying D/LR analysis on the longitudinal data from Study 2. The third aim is to evaluate the overlap and significance for the development of emergent literacy skills, reading skills, and reading disabilities of behaviors characteristic of Attention Deficit Hyperactivity Disorder. We will achieve this aim using SEM on the longitudinal data obtained in both studies. The fourth aim is to compare the predictive power of different metrics of preschool emergent literacy skills (e.g., growth rate, terminal skill level, initial skill level) for determining later reading skills. We will achieve this aim by using SEM and D/LR on the longitudinal data obtained in Study 2. The fifth and sixth aims are to evaluate the causal relations between preschool emergent literacy skills and both later emergent literacy skills and later reading. We will achieve this aim by using SEM of longitudinal data from both studies.